Riverview Apartments in Lake View, Florida was designed to meet a need for affordable housing for the older people of the south Florida area. Clearly in a hurry, the developer, First Florida Builders Corporation, gave main contractor Dylme Construction Company just 75 days to construct the 160-unit complex which consists of four interconnected structures.
To accomplish the task Dylme used the Outinord tunnel form technique, which is a cost effective and quick method of erecting a concrete structure. It has been used for many years in south Florida and in many parts of the world.
The Outinord tunnel technique is a system of erecting each layer of the structure using flying forms and then pouring concrete to form up the walls and floor of the structure. Workers strip and erect the forms in the morning and pour concrete in the afternoon. After the concrete has set, Dylme crews strip the forms and recycle them from the previous day’s work.
In addition to being reusable many times over, the forms are also rapidly adaptable to any number of configurations. In a matter of minutes carpenters can rearrange them, add or delete various accessories and have them ready for reinstallation.
“Cycle time is an important aspect of the project,” says First Florida Builders Corporation project supervisor Mike Brady. “Safety is our most critical concern on this job. Speed and productivity, while also very important, rank a distant second and third.
“We are building four interconnected four-storey structures that will have a total of 160 units. The pace that we have set for this job is such that safety is our most important concern. Our schedule is to have them built in 75 days, so speed is obviously a factor.” A project’s schedule cannot be kept without a knowledgeable and experienced crew, and the right equipment. Measuring between 7.3m and 9.8m (24ft to 32ft) in length, 2.4m high and 2.1m wide, each flying form weighs between 3.2t and 3.6t.
“Initially we thought that we would need a 150 ton crawler crane to fly the Outinord tunnel forms and handle the materials like concrete and block for this job. Fortunately, when Rick Wiebelt of R & J Crane came here to estimate the job’s needs, he was able to show us that their 80-ton rated Link-Belt LS-138H II could handle it,” says Brady.
The new LS-138H II plays a large part in the project. The crane operated at boom angles of 60O to 77O and working radii between 12.8m and 30m. Flying the forms and pouring concrete with a bucket are just two of its duties. They also use the crane to lift and place reinforcing steel bars and to supply concrete blocks to the upper floors of the buildings.
The LS-138H II lattice boom crawler has several improvements over its predecessor. It has been upgraded to a 72.6t (80 US ton) rating and has 61m (200ft) of conventional boom or 55m plus 18m (180ft plus 60ft) of boom and jib combination. Self-assembly has been improved by a new remote counterweight assembly and removal system. The crane has more stability because of a wider and longer lower, though the total transportation weight is less than 41t.
The crane also features a fine metering pump control for precise load movement control, which has been useful on the Riverview Apartments project. Operator Bob Tucholski, a 27-year veteran crane operator, says that he often finds himself working blind with only two-way radio directions to guide him.
“The forms that I lift weigh between 7,000lb and 8,000lb. The one thing constant about the job is the wind and it is ever changing. While this isn’t that much of a problem on the ground level floor it can become one as the forming progresses upward. It is imperative that I have a very stable machine to work with and a hard level surface to work from.
“There are times that my on-board computer indicates that I may be approaching the load limits. This is no time to be concerned with stability or responsiveness. I hold the key to the safety of the men working beyond my vision. I have to be right the first time. When the signalman wants a quarter of an inch up or down with an 8,000lb form hanging from the crane, he certainly doesn’t want three or four inches,” said Tucholski.
One of the first things the general contractor did was to construct a stable, well-compacted crane access road around the entire periphery of the finished building. This was an absolute must because the crane could be working from any position as the building’s construction progresses from the ground up.
“I don’t have the time to wait while they build me a level pad to make the lifts. I needed a level place to work from and a stable crane to work with. It is very important to have both. The additional 10,000lb lifting capacity, boom reach and faster travel speed of the new LS-138H II really do give me a leg up on safety.
“It wasn’t long ago that we would have been using a 150 ton machine instead. With the increased stability and added counterweight system, we can do the same work with the new 80 ton machine,” Tucholski says.
As the Outinord forms are reconfigured their weights change. It is vital to the safety and progress of the job that the crane operator knows precisely how much weight he is lifting and how far out he has to reach with it. This brings home the importance of rated capacity limiters, like the PAT El-65 on board this crane.
“Our operators now have heightened awareness of them and more confidence in them. That, combined with the operator’s experience, provides our customers an additional safety factor at no additional cost to them. Because of the typically high temperatures and humidity that we have in our work area, we have also equipped our crane’s operator’s cabs with air conditioners. That, too, is a safety factor as well as being a comfort component,” adds Wiebelt.
